This invention relates to an antenna module suitable for use with electronic equipment which conducts radio communications, such as a mobile communication terminal or a personal computer.
In recent years, there has been a growth in portable terminals having a chip antenna installed therein to conduct radio communications of data with other electronic equipment in addition to a whip antenna or an internal antenna provided for voice communications.
There has also been a growth in conducting data communications by radio using a radio LAN, etc., in portable-type mobile electronic equipment such as a notebook personal computer, and there has also been a growth in electronic equipment each containing a chip antenna.
Further, miniaturization and low power consumption have been indispensable for recent mobile telephones, notebook computers, etc., and miniaturization of an antenna apparatus has been demanded. Providing an antenna with a wide band has been required with an increase in the transmission capacity in recent years. Further, providing a wide band has been required increasingly in a multicarrier system such as an OFDM system (orthogonal frequency demodulation multiplex).
To increase the load capacity of an antenna to provide the antenna with a wide band, an antenna module with an additional conduction section added to the tip of the antenna is proposed, for example, in JP-A-2002-124812 or JP-A-10-247806. FIGS. 37 and 38 are top views of antenna modules in related arts and show the case where an additional conductor section is added to the tip of an antenna element.
Numeral 100 denotes an antenna module, numeral 101 denotes a meander antenna, numeral 102 denotes a feeding section, and numeral 103 denotes an additional conductor. The meander antenna 101 is formed of a board pattern, etc. The additional conductor 103 is formed at the tip of the meander antenna 101 and the tip is an open end. A signal current is supplied from the feeding section 102 and the supplied signal is emitted according to the resonance frequency of the meander antenna 101. Reception is also performed in a similar manner. At this time, with the additional conductor 103 as a load capacity, the load impedance seen from the feeding section 102 increases, the peak of the frequency curve becomes gentle, and the frequency band is enlarged.
FIG. 38 shows how two meander antennas 101 are arranged in parallel to deal with multiple resonances and a separate additional conductor 103 is formed at the tip of each of the meander antennas 101.
However, to form an additional conductor at the tip of a pattern antenna such as a meander antenna, the pattern antenna itself requires a large area and thus the antenna module is upsized, which is a problem.
In a recent portable terminal, notebook personal computer, etc., an antenna module of multiple resonance has been required for one terminal to cover a plurality of frequency standards. Thus, if a plurality of antennas are arranged in parallel, each antenna requires a separate additional conductor, the antenna module is upsized, and apparatus incorporating the antenna module becomes difficult to miniaturize, which is a problem.
Particularly, to provide separate additional conductors, it is necessary to provide each antenna with a wide band with each additional conductor and each additional conductor is upsized, leading to upsizing the antenna module containing the additional conductors, which is a problem.